FIGURE 3.

Senescent astrocytes present impaired neuritogenic and synaptogenic properties in vitro. (a) Neural progenitor cell cultures were maintained in DMEM (vehicle), ACM‐Control, or ACM‐Senescent for 2 DIV. (b–d) The number of primary neurites per cell was quantified based on β‐Tubulin III immunostaining. (e) Neural progenitor cells treated with ACM‐Control showed increased number of neurites compared with those treated with DMEM (p = 0.0097). In contrast, neural progenitors treated with ACM‐Senescent exhibited reduced neurite number compared with ACM‐Control (p = 0.0044). (a, f–h) Mature neurons (12 DIV) were treated with DMEM, ACM‐Control, or ACM‐Senescent for 3 h, and the number of synapses was quantified based on synaptophysin/spinophilin colocalization puncta. (i) Neurons treated with ACM‐Control showed increased percentage of colocalized puncta compared with those treated with DMEM (p = 0.0083). Conversely, ACM‐Senescent reduced the number of synapses compared with ACM‐Control (0.0010). Significance was determined using one‐way ANOVA with Tukey's multiple comparisons test. Error bars represent ±SEM. Individual data points are plotted and represent individual cultures (n = 3–9 cultures per experimental condition). Scale bars, 20 µm